Flavin coenzyme analogs, synthetically modified at various key ring loci, will be used to analyze and factor out elements of flavin redox function, such as two electron/one electron capacity, sites of entry and exit of electrons, and nature of O2 reductive activation and splitting. Experiments will focus on methanogenic coenzyme factor 420, on monooxygenases such as p-hydroxybenzoate hydroxylase, cyclohexanone monooxygenase, and amine N-oxygenase. E. coli membranous D-amino acid dehydrogenase will be reconstituted with coli membrane vesicles and coupling to active transport of solutes probed.